An agricultural combine is a common and well-known machine for harvesting crop materials. Agricultural combines are available in various designs and models to perform the basic functions of reaping crop materials from a crop field, separating the grain from the non-grain crop materials, and discarding the non-grain crop materials back onto the crop field.
A typical combine includes a crop harvesting apparatus, or header, which reaps ripened crop plants from the crop field and feeds the crop materials to a separating or threshing system. Several different types of threshing systems are available, such as rotary threshers and straw walkers. Regardless of the type of threshing system used, the thresher separates the course non-grain materials from the grain heads. The course non-grain material primarily consists of grain stalks and exits the thresher along its rear end. The grain heads, on the other hand, exit the thresher along the bottom side of the thresher and pass to a series of moving sieves. The sieves separate the grain from the unwanted fine materials, sometimes referred to as chaff. After separation, the grain is directed to a grain bin through an augering system, and the unwanted fine materials exit the sieves along the rear end.
The grain bin serves as a temporary onboard storage location for the grain. Typically, the grain bin is positioned above the threshing system and can have a capacity of as much as 200 bushels for larger combines. As the combine harvests the crop field, the grain bin periodically becomes filled with grain and must be emptied to allow the combine to proceed. The grain is then transferred from the grain bin to a truck or a grain cart through an unloading auger.
The unloading auger is a well-known device to those skilled in the art of combines. Most manufacturers of combines have adopted a similar configuration for the unloading auger. In this common configuration, the unloading auger is positioned along the upper side of the combine with the infeed section of the auger located adjacent to the grain bin. The infeed section is pivotally attached to the combine to allow rotation about a nearly vertical axis. A 90° elbow connects the infeed section to a long horizontal section. The horizontal section can then rotate in a generally horizontal plane around the infeed end. With this design the unloading auger can be rotated out to a 90° angle from the combine to allow unloading into a truck or grain cart. After unloading, the unloading auger is rotated back so that the horizontal section trails towards the rear of the combine with the exit end located near the combine's rear end.
While this configuration for the unloading auger has been a convenient solution for the need to unload the combine's grain bin, the long length of the auger's horizontal section presents a number of problems for both the farmer and the manufacturer. These problems are exacerbated by the increasing production capacity of newer combines which requires ever longer unloading augers.
In order to satisfy farmers' demands for more efficient harvesting equipment, manufacturers have regularly increased the width of the combine header. Currently, some combine headers are as wide as forty feet, and even larger widths are eventually possible. In addition, farmers are increasingly turning to the use of grain carts and unloading the combine's onboard grain bin into the adjacent travelling grain cart while the combine is still harvesting through the field. Frequently, the grain cart is towed by an agricultural tractor which has dual sets of tires installed on it. With this unloading arrangement, the unloading auger must extend over a substantial distance in order to reach the grain cart, including the width of the header, the safety clearance between the header and the tractor tires, and the width of the grain cart and tractor.
Current unloading augers also prevent farmers from implementing a technique known as controlled traffic pattern. In this application the combine unloads grain into an adjacent travelling grain cart like previously described. However to avoid additional soil compaction, the tow tractor and grain cart travel along the combine's prior tire path which is located one swath away from the combine's current travel path. Thus, by reusing the same tire path that has already been created by the combine, more ground soil is left uncompacted, which allows better growing conditions for subsequent crops. Controlled traffic pattern harvesting, however, requires even longer unloading augers than are generally available in order to span the long distance between the combine's current and prior tire paths.
Typically, prior art unloading augers are lengthened by extending the length of the horizontal section and allowing an extended portion to extend beyond the rear end of the combine. This extended portion can raise the manufacturer's shipping costs for the combine significantly however. Shipping costs are often calculated based on the volume of the shipped product. This is especially true when a combine is shipped overseas on a ship. In these cases, if the manufacturer chooses to install the unloading auger at the factory, the extended portion can require as much as 10% more shipping volume than would otherwise be required, substantially increasing the cost of shipping. On the other hand, the manufacturer may choose to ship the unloading auger separately to avoid this cost penalty. However, this alternative suffers from the problems of ensuring that the correct parts are shipped to the customer and that they are properly installed once received.
This extended portion also requires additional storage space on the farm. Farmers typically store their agricultural equipment in large buildings when the equipment is not being used in order to minimize weather related deterioration. Hereto, the extended portion limits the amount of equipment that can be stored in the storage building because other equipment must be positioned behind the end of the unloading auger instead of directly behind the combine's rear end.
Problems also occur when the farmer is operating the combine during harvesting operations. The long horizontal section of the unloading auger makes the overall length of the combine extra long and creates a collision hazard for the extended portion. Farmers operate their combines around a variety of different obstacles, which can be accidentally struck by the extended portion. Examples of these obstacles include trees, telephone poles, buildings, and other vehicles. The risk of rear end collisions is especially great with combines because the large size of the combine and the minimum amount of rearward visibility makes it difficult to see nearby obstacles. When a collision does occur with the unloading auger, the costs to the farmer can be quite high. Not only is the object struck damaged, but the unloading auger will likely be disabled. As a result, the farmer incurs repair costs, and the harvesting operation is delayed until the unloading auger can be fixed.
To minimize the risk of rear end collisions, some countries have implemented transportation regulations that require a combine to be able to turn around within a specified radius without any portion of the combine passing outside the radius. This type of regulation requires that the combine be designed as compact as possible. Satisfying a regulation like this is especially difficult with an unloading auger that extends beyond the rear end of the combine.